Boise State defensive end Kharyee Marshall has endured four painful, frustrating years to reach his senior season.

He has missed parts of the last two seasons and three of four spring practice sessions, including this past spring, because of injuries — two to his shoulders and two to his knees.

He entered this fall camp healthy and among the top contenders for playing time at the stud end position, which is the hybrid position that requires a combination of run-stuffing, pass-rushing and pass-defending skills.

“The only thing I can do is stay positive about it,” Marshall said of his experience at Boise State. “If I stay positive, then I know my mind’s going to be, ‘OK, I can do this. I can get on the field and work my butt off and get back to where I want to be.’ ”

Marshall made a career-high 18 tackles last season. He injured a shoulder just before halftime in the MAACO Bowl Las Vegas, which forced him to miss spring ball.

He’s one of five players competing at stud — junior Tyler Horn, who also plays tackle; redshirt freshman Sam McCaskill; and true freshmen Kamalei Correa and Gabe Perez are the others.

Marshall knows he’s got a big opportunity in front of him. He also knows he’s got to make up for a lot of lost practice time.

“I’m just out there trying to improve and get better every day,” he said. “There’s a lot I still need to work on. I was out in the spring, so I didn’t really get a chance to work on my technique with the other guys.”

And whatever his role on game day, he must deliver some leadership. He’s the only senior defensive end and one of just two senior linemen (tackle Ricky Tjong-A-Tjoe is the other).

“Shea (McClellin) helped me when I was young,” Marshall said of the NFL first-round pick. “Now I’m starting to help these young guys while I’m a senior. That’s what has helped us get better each and every year.”

The line has served as the backbone of the Broncos’ dominant defense over the past five years. Most of those stars are gone, but the edge remains.

“We’re hungry,” Marshall said.

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Junior Demarcus Lawrence is the returning starter at the other end position. He led the Mountain West with 9.5 sacks last year as a junior college transfer.

If the first week of fall camp is any indication, Lawrence will be better this year.

“We talk about staying hungry all the time — stay humble, but we’ve got to stay hungry, too,” defensive line coach Andy Avalos said. “That’s the approach he’s brought out here so far this camp. And it’s exciting to see a guy who’s had the success he’s had and yet he still comes out and works the way he does day in and day out. He’s setting a good example for the younger guys in our group.”

Lawrence made strength gains during the offseason, Avalos said, and has dedicated himself to improving his game.

“He loves to watch the film,” Avalos said. “That’s a guy right there who loves watching football. He’s constantly breaking himself down, the things he can get better at.”

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Avalos on Horn, who moved from end to tackle late last season and might have stayed there if Sam Ukwuachu hadn’t been dismissed from the team in the spring: “T-Horn’s awesome. Last year, he played every position across the front. Does he necessarily have the weight to play inside? Not ideal. But he does a great job when he jumps in there. And he’s got the athleticism when we put him on the edge. We do do a fair amount of stuff on defense. For him to be able to handle all that stuff mentally speaks volumes to his preparation.”

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Highlights from this morning’s veterans practice:

— Redshirt freshman stud end Sam McCaskill, who had a strong spring, continued to cause problems as a pass rusher. He recorded a sack, forced fumble and pass breakup.

— The first-team offense drove into field-goal range during a game-like drive. Junior Dan Goodale capitalized with a 37-yard field goal. The defense won the battle among second-teamers.

— Junior cornerback Deon’tae Florence made the catch of the day, a leaping interception just outside the goal line. He stuck one foot just inside the sideline.

— Sophomore tight end Holden Huff, running over a cornerback downfield, and Lawrence, catching a tailback in the backfield, delivered a couple of big hits. The Broncos were in shoulder pads and helmets. They put on full pads Friday, when full-squad practices begin.

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— Sophomore right guard Marcus Henry, who has been with the first team since the spring, was coach Chris Petersen’s camper of the day. Redshirt freshman Mario Yakoo is pushing him. “Marcus has been competing very hard and he has been working his tail off since last spring,” Petersen told BroncoSports.com. “He certainly showed up today.”

ESPN The Magazine gives Boise State a new name in its college football preview, an ode to the Broncos’ success fighting the system: Screw U.

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Here is my updated position-by-position roster. It reflects a couple minor changes and the coaches’ decisions to split stud end into its own position on the roster and remove the nickel designation from the strong-side linebacker.